PHAEOPHYCEAE 243 



Zoospores from sporangia begin to germinate within 24 hours, form- 

 ing dioecious, filamentous gametophytes bearing oogonia and anther- 

 idia. The fertilized egg at once begins to develop into the Laminaria 

 plant. If you succeed in getting gametophytes, fix in 10 per cent for- 

 malin and follow the Venetian turpentine method. 



Nereocystis. — This immense kelp, often more than a hundred feet 

 long, is abundant along our northern Pacific Coast. July and August 

 are good months for sporangia. The immense sori, often more than 

 30 cm. long, contain millions of sporangia, and sori of various ages are 

 found on a single leaf. The Chicago formula is good for sections of 

 sporangia. Lay one leaf upon another for a support and cut the sori 

 into pieces about 5 mm. scjuare. Sporangia at the shedding stage will 

 be found just as the big sori are dropping out from the leaf. The reduc- 

 tion of chromosomes will take place in sori nearer the tip of the leaf. 

 The Chicago formula, with the iron-alum haematoxylin stain, follov»^ed 

 by a minute in safranin to touch up the mucilaginous caps, makes a 

 good mount. 



Nereocystis has dioecious, filamentous gametophytes, like Lamina- 

 ria. The zoospores from sori which are just falling out from the leaves 

 germinate promptly; but antheridia and oogonia appear 10 or 11 

 weeks later. The young sporophytes, developing from fertilized eggs, 

 continue to be formed for at least a year. 



If you should start a culture, sterilize the sea water, take a sorus 

 just as it is dropping out from the leaf, wash it thoroughly to get off as 

 much as possible of the diatoms, bacteria, and other things, and don't 

 put too much of the sorus into the jar; two or three pieces, a centimeter 

 square, is enough. You can save two or three unsuccessful seasons by 

 reading carefully a paper by Dr. Lena A. Hartge, who succeeded in 

 keeping cultures growing for more than a year ( Nereocystis, Publica- 

 tions of the Puget Sound Biological Station, 5:207-237, 1928). A pa- 

 per in the same journal on "Gametophytes of Costaria costata," by 

 Miss Laura Angst, was published a year earlier. The gametophytes of 

 Costaria mature in half the time required by Nereocystis; consequent- 

 ly, the chances for securing gametophytes are more favorable. 



Follow the directions given for Nereocystis. 



Cutleria. — This alga deserves a place in any course in morphology, 

 if the course is thorough enough to permit the study of three members 

 of the Phaeophyceae. These three should be Ectocarpus (or Pijlaiella), 

 Cutleria, and Fucus. Cutleria is not found on the American coasts, but 



